Water-repellent and preservative composition and method of use



United States Patent 3,413,399 WATER-REPELLENT AND PRESERVATIVECOMPOSITION AND METHOD OF USE Donald Clifford Wehner, Stamford, Conn.,assignor to American Cyanamid Company, Stamford, Conn., a corporation ofMaine No Drawing. Filed Nov. 23, 1965, Ser. No. 509,406 6 Claims. (Cl.424-131) ABSTRACT OF THE DISCLOSURE A water-repellent and preservativemixture, for application to textiles and cellulose products, of analuminum or zirconium salt and the terephthalic, isophthalic or malicacid salt of an alkyl guanidine.

This invention relates to compositions and methods for preserving poroussubstrates from microbial deterioration and for impartingwater-repellency thereto,

By porous substrates is meant formed textile materials and celluloseproducts which are subject to microbial attack and which are receptiveto water-repellent finishes containing aluminum or zirconium salts.Water repellency is here distinguished from waterproofing in that theformer quality results from deposition of a hydrophobic substance on thefibers composing the textile material or cellulose product, leaving theinterstices between the fibers substantially unfilled and unaltered. Asa result, air and water vapor can pass through the textile material orcellulose product. In contrast a waterproofed substrate is one in whicha continuous film of the hydrophobic substance is applied to thesubstrate so as to render it impervious in either the liquid or vaporphase. The degree of water-repellency is dependent on the arrangementand closeness of the fibers in the textile material or cellulose productas well as on the efficiency of the water-repellent.

By textile material is meant formed fibers or fabric, either woven orfelted containing wool, cotton, silk, synthetics or blends of two ormore of these types. The cotton may be in the form of regeneratedcellulose, linen, jute, ramie, hemp and the like. The synthetics includeknown materials such as rayon, nylon, cellulose acetate, polyesters,acrylics, as well as modifications and blends thereof.

By cellulose products is meant paper, cardboard, and various cellulosebuilding or construction materials such as fiberboard and the like whichare exposed to moisture and therefore subject to water and microbialdamage.

Such textiles and cellulose products may take any shape, size or formand are articles which are intended to be re-used. Specificillustrations of such articles would include wearing apparel,handkerchiefs, diapers, dish and bath towels, books and book covers,washable cloth toys, dolls and similar playthings, hospital and hotelsheets and pillowcases, hospital and examination room bathrobes andslippers, barbers and beauticians cloths, and similar articles.

A major objective in the manufacture of textile materials and celluloseproducts is to provide not only a finish which is water-repellent butalso one which inhibits the growth of microorganisms or is toxic tomicroorganisms attracted to or residing on the porous substrate. Thepresence of these microorganisms often results in the harmful conditioncalled mildew, rotting, and other forms of decomposition, and promotesdispleasing odor. These microorganisms include a wide variety of fungiand bacteria and their growth is particularly promoted in textile andcellulosic materials worn close to the body such as sweat shirts anddiapers and in tenting, cordage,

Patented Nov. 26, 1968 awning and other fabrics exposed to high moistureand humidity.

Compositions containing antimicrobial agents should be active at lowconcentration against a broad spectrum of microorganisms. Moreover, theyshould be non-toxic and non-allergenic to the touch. Furthermore, ifapplied to a textile material, the composition should be substantiallyresistant to leaching out under home and commercial launderingconditions and should impart little or no modification of the hand ofthe textile.

A known class of compounds exhibiting high activity in lowconcentrations against a wide variety of microorganisms is representedby the formula (RNH( l-NH2)11-A (I) wherein A represents an acidic saltforming group, n is the small whole number 1 or 2, and R is an alkylradical containing from about 8 to 18 carbon atoms, straight or branchedchain, but preferably straight chain of from about 10 to 14 carbonatoms. These compounds are also characterized as the acid or normalsalts of alkyl guanidines. Numerous acids, both organic and inorganic aswell as monobasic and polybasic, have been employed to form the salts.Such acids have included for example sulfuric, hydrochloric, nitric,phosphoric, acidic, propionic, butyric, malic, phthalic, benzoic, boric,and the like, as further described with application in US. Patents2,906,595, 2,867,562, and 2,921,881.

Although providing anti-microbial activity in other environments, thecompounds represented by the above formula are surprisingly notuniformly effective as a class when applied to porous substrates incombination with a water-repellent material containing an aluminum orzirconium salt. Thus certain members, e.g., the alkyl guanidine sulfatesand 2-ethyl hexanoates, either are too insoluble for contact withharmful microorganisms or have such extreme water solubility, e.g., thealkyl guanidine acetates and hydrochlorides, as to be easily washed outduring laundering or cleaning. Moreover, of those limited number ofcompounds providing the proper solubility for contact with the harmfulmicroorganisms while avoiding leaching out, it has surprisingly beendiscovered that only a certain few maintain their activity whencontacted with a water-repellent material containing an aluminum orzirconium salt. While not fully understood, it appears that when analkyl guanidine salt having a free carboxyl group is employed, e.g.,phthalic acid or phthalic anhydride salt of n-dodecyl guanidine, thefree acid group reacts in some manner with the aluminum or zirconiumsalt in the waterrepellent, thereby rendering the alkyl guanidine saltsinactive.

Accordingly, effective water-repellency and antimicrobial activity isprovided by a composition which comprises a water-repellent mate-rialcontaining an aluminum or zirconium salt and an antimicrobial compoundof the formula wherein R is alkyl as defined above and A is adicarboxylic acid selected from the group consisting of terephthalicacid, isophthalic acid and malic acid. The salts represented by theabove formula are not rendered inactive by the aluminum or zirconiumsalts commonly employed in or as water-repellents, exhibit high levelsof toxicity in low concentrations, and have the proper solubility forcontact with microorganisms while also providing resistance to leachingout.

The aluminum or zirconium salts are any of the wellknown compoundsemployed as water-repellent agents.

These include aluminum sulfate (alum), aluminum acetate, aluminumformate, zirconium oxychloride, zirconium oxynitrate, zirconium acetate,and ammonium zirconium dicarbonate.

In the past, these salts have provided a deg-rec of waterrepellency whenapplied alone or when generated in situ (as by reaction of aluminumoxide or zirconium oxide with acetic or formic acid) on a poroussubstrate. In time, however, wate-r-repellency of textiles was improvedby combining the aluminum or zirconium salt treatment with an alkalimetal soap process, thereby providing a complex insoluble hydrophobicmetal soap on or within the porous substrate. Later, water-repellency oftextiles was further improved by combining the aluminum of zirconiumsalt treatment, alone or with an alkali metal soap, with an applicationof a parafiin wax or wax-like material such as silicone orperfluorocarbon resins. These materials are applied either in a two-bathprocess or, preferably, in a single bath.

Best results by oneor two-bath applications depend on the preparation ofa stable wax emulsion. This is provided, in the case of one-bathprocesses for imparting water-repellency to textiles, by addition ofknown and commercially available protective colloids such as gelatin,fish glue, bone glue, de-acetylated chitin, hydrolysed bovine bloodalbumin, polyvinyl alcohol, and sodium polyacrylate. Numeroussurface-active agents are also employed with or as substitutes for theforegoing watersoluble macromolecules. These include pOlyethenOxycompounds, e.g., ethylene oxide adduct withN-hydroxyethyl-N-octadecylaniline, ethylene oxide-oleic acid adducts,non-ionics such as a mannitan fatty ester, cationics such asstearoxyethyldimethylbenzylammonium chloride, and combinations ofcationics and non-ionics.

It is also conventional to employ in such compositions diluents andsolvents such as mineral spirits, nonyl phenol, animal or vegetableoils, and other organic and inorganic liquids.

In the case of cellulose products such as paper and cardboard, theprocess of imparting water-repellency is commonly inherent to the sizingoperation. Among the numerous known sizing methods which also impartwaterrepellency may be mentioned preparation of a rosin or paraffin waxdispersion and at the appropriate moment precipitating the rosin or waxonto the fibers by addition of an aluminum or zirconium salt, most oftenaluminum sulfate -alum), in quantity sufficient to provide a pH of 4 to5.

The foregoing treatments suffer from the same defi ciency as textileswhen it is desired to preserve the substrate by application of an alkylguanidine salt as an antimicrobial agent. The instant invention obviatesthis difficulty in substantially the same fashion as already described,i.e., by employing the alkyl guanidine salts of Formula II above which,surprisingly, are not rendered inactive by the aluminum or zirconiumsalts conventionally employed as precipitating and water-repellentagents in the treatment of cellulose products.

A particularly preferred example of one-bath compositions is theso-called acid/wax combination. This is an emulsion containing asessential ingredients the aluminum or zirconium salt, a wax, and aprotective colloid such as gelatin. The emulsion is stabilized bymaintaining an acid pH, generally in the range of about 2 to 6 butpreferably or less. The acidity is often provided by addition of amineral or organic acid such as acetic acid. Typically such dispersionsare made by adding alum to a solution of alkali metal soap in thepresence of gelatin or fish glue. The aluminum salt should be present ina stoichiometric excess over the soap. The wax is generally ahydrocarbon wax and may contain a high melting wax such as ceresin. Thealuminum salt is usually aluminum acetate or aluminum formate and thezirconium salt is usually the oxichloride or the acetate. Sometimes thealuminum or zirconium salt is formed in situ by an admixture of aluminumoxide or zirconium oxide with acetic or formic acid. For example, onecommercial composition comprises 17% paraflin wax, 2.5% bone glue, 3.0%A1 0 7.0% formic acid, 0.7% wood rosin, 0.2% potassium hydroxide andsufiicient Water to make 100%. The wax can be added molten or as -apreformed emulsion.

From the foregoing, it will be evident that the present inventioncontemplates and includes compositions comprising any of the abovealuminum salts or zirconium salts and an alkyl guanidine salt of FormulaII above, as dry, aqueous, or non-aqueous solutions or dispersions, aswell as such compositions containing additional ingredients Which do notsubstantially interfere with the water-repellent and antimicrobialproperties of the two essential ingredients.

In accordance with the method of the invention the aluminum or zirconiumsalt water-repellent material and antimicrobial agent are applied inadmixture or separately to the porous substrate by any convenient meanssuch as dipping, padding, spraying, exhaustion, or the like, for aperiod of time suflicient to fix the composition onto the substrate.

The total amounts of aluminum or zirconium salt and alkyl guanidine saltshould be sufiicient to provide both water repellency and antimicrobialactivity. Proportions and total amounts may be varied over wide rangesdepending, for example, on the thickness of the substrate and theduration of effectiveness required for the particular use for which thetreated substrate is intended. As a general rule, good antimicrobialactivity results when the substrate contains from about 0.01% to 5% ofthe antimicrobial agent based on the weight of dry substrate. If thesubstrate is a textile material, the preferred range of antimicrobialcompound is from about 0.25% to 0.5% based on the weight of dry fabric.When the aluminum or zirconium salt and alkyl guanidine salt are appliedfrom an admixture, such dispersions typically comprise up to about 40%total solids of which the proportion of aluminum or zirconium salt toalkyl guanidine salt will range from about 1:10 to 10:1.

The literature on the subject of water-repellency of porous substratesincluding textile materials and cellulose products is extensive. Afairly comprehensive treatment is Waterproofing and Water-Repellency, I.L. Moilliet, Editor, Elsevier Publishing Co., New York, 1963,particularly Chapters 3, 6, 7, 8 and 11. This text is incorporatedherein by reference.

The following examples further illustrate the invention but are notlimitative thereof except as indicated in the appended claims. All partsand percentages are by weight unless otherwise specified.

Example 1 To demonstrate the utility of alkyl guanidine salts as fabricpreservatives, a series of cloth samples x 80 cotton percale) weretreated with several salts of n-dodecyl guanidine and then subjected toa soil-burial test as described in Method 5762, Mildew Resistance ofCloth; Soil Burial Method of Federal Specification CCC-T-19l, TextileTest Methods. In accordance with this specifica tion, the cloth stripswere treated with 0.5% and 0.25% (based on weight of dry fabric) ofn-dodecyl guanidine hydrochloride, n-dodecyl guanidine acetate,n-dodecyl guanidine acid phthalate, n-dodecyl guanidine terephthal ate,and n-dodecyl guanidine 2-ethylhexanoate by dissolving the toxicant inisopropanol and padding the solution onto the cloth samples. Afterdrying, the cloth samples were buried in soil for six weeks The clothsamples were thereafter removed and examined for deterioration.Untreated cloth samples and those treated with n-dodecyl guanidinehydrochloride, n-dodecyl guanidine acetate, and n-dodecyl guanidineZ-ethylhexauoate were found to be so completely rotted that they couldnot be handled without disintegrating. The 0.5% level samples ofn-dodecyl guanidine acid phthalate and n-dodecyl guanidine terephthalateby visual inspection appeared to be unaffected by the burial while atthe lower concentration of each, 0.25%, disintegration of the clothsample was only partial. As a positive control one sample of cloth wastreated with 0.1% of copper 8-hydroxyquinolinolate (a well-known fabricfungicide). This sample showed deterioration intermediate that resultingfrom the two concentrations of n-dodecyl guanidine acid phthalate andn-dodecyl guanidine terephthalate.

Example 2 In another series of similar tests, separate samples of awningmaterial (cotton duck) were treated with n-dode-' cyl guandine acidphthalate and n-dodecyl guanidine terephthalate to give concentrationsof 0.4% based on weight of dry fabric. The toxicants were applied from acommercially available acid/wax emulsion which contained an aluminumsoap. Upon completion of the burial period, it was found that then-dodecyl guanidine terephthalate-treated cloth had retained almost allof its original tensile strength whereas the sample treated withn-dodecyl guanidine acid phthalate had lost almost as much strength asthe untreated control (almost total disintegration). In efforts todetermine why n-dodecyl guanidine acid phthalate provided goodprotection when used alone but failed when in combination with anacid/wax waterproofing agent it was found that the n-dodecyl guanidineacid phthalate formed an intractable precipitate with aluminum acetate(present as a complex aluminum soap in the acid/ wax mixture) whenheated whereas n-dodecyl guanidine terephthalate was not effected bysuch mixing.

Example 3 In another soil burial test conducted as described in Examples1 and 2 with n-dodecylguanidine malate as the antimicrobial agent in anacid/Wax emulsion of substantially the same composition as described inExample 2, good Water-repellency and resistance to rotting was noted.Moreover, this salt and n-dodecylguanidine isophthalate were not foundto precipitate when separately admixed with aluminum acetate, therebydemonstrating that toxicity is not lost by reaction with aluminum saltwater-repellents.

Iclaim:

1. A water-repellent and preservative composition which comprises awater-repellent compound selected from the group consisting of aluminumand Zirconium salts and an antimicrobial compound of the formula whereinR is a straight-chain alkyl containing from about 10 to 14 carbon atomsand A is selected from the group consisting of terephthalic acid andisophthalic aicd and wherein the proportion of said water-repellentcompound to said antimicrobial compound is in the range of from about 1:10 to 10: 1.

2. The composition of claim 1 wherein A of the formula is terephthalicacid.

3. The composition of claim 1 wherein A of the formula is isophthalicacid.

4. A method of imparting both Water-repellency and resistance tomicrobial deterioration to a member of the group consisting of paper,cardboard, fiberboard and formed textile materials which comprisesapplying thereto an effective amount of a water-repellent andpreservative composition as defined in claim 1.

5. The method of claim 4 wherein A of the formula is terephthalic acid.

6. The method of claim 4 wherein A of the formula is isophthalic acid.

References Cited UNITED STATES PATENTS 2,713,008 7/1955 Schulenbury117138.5 2,789,956 4/1957 Eder 117-135.5 2,906,595 9/ 1959 Pelcak 167-222,921,881 1/1960 Lamb l67306 3,031,335 4/1962 Segal 117135.5

ALBERT T. MEYERS, Primary Examiner.

S. I. FRIEDMAN, Assistant Examiner.

